The present invention relates to an arrangement including a plasma display screen.
Currently marketed television sets having plasma display screens require a substantial investment as regards the shielding of electromagnetic fields. They require inter alia a solid aluminum or metal housing in combination with a metal-coated front plate in order to enable the statutory requirements as regards electromagnetic compatibility to be met. These shielding measures are expensive and, moreover, they increase the weight of the sets.
It is an object of the present invention to improve the circuits and power leads for driving such a plasma display screen in such a manner that the emission of electromagnetic waves is reduced and additional shielding measures are superfluous.
According to the invention the object is achieved in a first manner in that in an arrangement including a plasma display screen having cells for the generation of pixels between a transparent plate facing the viewer and a rear wall and having electrical contacts for contacting the cells in the areas of opposite outer edges of the rear wall, which contacts are connected to electronic circuits, arranged on the outer side of the rear wall which faces the cells, by means of current supply leads which extend substantially parallel, in such a manner that the current supply leads end, electrically isolated, in a narrow contact area, where electrical contact is established between the current supply leads, on the one hand, and the electrical circuits, on the other hand.
Thus, by a modified arrangement of the circuits for driving the plasma display screen, the current routing between the display boards and the electrodes of the pixels of the display screen is changed in such a manner that the emission is reduced. For this purpose, the current supply leads to the connections of the electrodes of the plasma display screen are not only present in the peripheral areas, as customary until now, but they are present over the entire back side of the plasma display screen and end, coming from both sides, in a narrow contact area, which extends perpendicularly to the current supply leads. This area of the plasma display screen precludes an antenna-like emission of electromagnetic fields, because the current supply leads coming from both sides end, electrically isolated, directly adjacent one another. Moreover, as a result of such an arrangement the electromagnetic fields emitted by the current supply leads to the electrodes on principle combine with the fields emitted by the current supply leads that extend on the inner side of the rear wall and cancel one another in the ideal case. Thus, an expensive and weight-increasing shielding as in conventional plasma display screens is superfluous. Since both the connections for the electrodes disposed on the front plate and for the electrodes disposed on the rear wall can be led out and arranged at the periphery of the rear wall, this enables all the electrodes to be connected to the current supply leads and to be led to the contact area.
By means of a printed conductive connection as defined in claim 2 the current supply leads can be manufactured cost-effectively and simply from the point of view of production engineering, in that they are deposited on the rear of the plasma display screen.
The embodiment as defined in claim 3 enables the use of the known connections via flexible leads to be continued in order to obtain a shielding in accordance with the invention as defined in claim 1.
The present object is achieved in a second manner with the aid of the subject matter of claim 4. Thus, the current paths to the contact areas of the electrodes can also be shortened in that the circuits for driving the pixels are arranged directly on the outer side of the rear wall of a plasma display screen. This once again shortens leads to the electrode connections. Moreover, common buffer capacitors shorten the current paths between the electronic circuits for the driver stages of the X electrodes and the Y electrodes. In combination with the embodiment as defined in claim 1 this enables a particularly effective suppression of the emission of electromagnetic waves. At the same time, a solution using common buffer capacitors is substantially cheaper than one using separate buffer capacitors for each driver stage.
With the embodiment as defined in claim 5 the advantages of the invention are obtained in an end product such as a television set or a monitor, which can consequently be manufactured more cheaply.